Screw connection is a common method for fastening two components. Usually, a via hole is set in one of the components while a screw threaded hole is set in another one of the components, and a screw is inserted into and rotational-engaged with the screw threaded hole through the via hole when it is necessary to fasten the two components by using screw thread, and finally, the two components are fastened together due to the effect of the screw head and the screw thread. In the connection method above, space is occupied and appearance of product is affected due to existing of the screw head. Therefore, it is necessary for providing a screw threaded fastening component without screw head.